Piston ring



D. M. SMITH PISTON RING Filed Nov. 10, 1930 4. A K w d Y G C ,Iii Wl il.F H a W. f. Il f. a

Patented Nov. 17, 1931 UNITED sraras PATENT orrlcr.

DALLAS I. SMITH, OF WEBSTER GROVES, MISSOUB, ASSIGNOLR T MCQUAY-NOBBISMANUFACTURING COMPANY, @2F ST. LOUIS, MISSOURI, .A CORPOBTION 0E' DELA-wenn PISTON RING application aies november in, leso.' serial ne. tenses.

My invention relates to piston rings and more particularly to pistonrings lor use in internal combustion engines the operation of whichrequires a substantially high unit ra- 5 dial pressure between thecylinder contacting face of the ring and the vvall of the cylinder inwhich reciprocates the piston Whereon the ring is used.

Some internal combustion engines because 1o of designed characteristicsrequire that the rings used therein have a unit radial pressuresubstantiallyv higher than that developed in piston rings ofconventional design. All piston rings comprising resilient split bandsi5 or piston rings otherwise rendered inherently elastic are springsandv depend upon theirY inherent elastic deformation or reaction vtoproduce'them against the cylinder wall. The

amount and strength of this reaction or dei-` -30 ormation depends uponthe material Vof which the ring is made. That is, if a coniparativelystrong material is used, the thickness of the ring and the amount ofdeflection can be great enough to produce very large stresses in thematerial, which stresses to a large degree account for largereactionsand, in turn, produce what is known as ring stiffness ortension. Ring thicknessesand resultant deflections have been increaseduntil a.

limit almost has been reached for materials generally used in themanufacture of piston rings. Cast-iron, the material in most common use,is not especially strong and in piston rings the maximum stressdeveloped is approximately thirty-tive thousand pounds per square inchtransverse load. When the cylinder contacting face is substantially thewidth of the body of the piston ring yand the ring is loaded to a stressof thirty-ve thousand pounds per square inch the unit radial pressuredeveloped on the contacting face of the ring and translated into poundsper square inch area thereof is approximately eighteen and one-halfpounds per square inch and such a unit pressure is quite high and forordinary purposes is considered sullicient.

However, as stated above, there is an ncreasing needk under certainconditions for rings having higher unit radial pressures in order thatthe pressure against tne cylinder Wall developed in the ring will hesufficient to prevent the escape or gases under high pressure and toscrape :troni the cylinder wall oil that might otherwise reach thecombusytion chamber. raise, regardless ol the ragreatly increased Without increasing the libre' stresses 1n tne ring and, therefore, continuingto use the same materials'that have been used in the past; and a furtherobject oil my .invention is to'prevent oil 'from building up between theface ot' the ring and tne cylinder "Wall by .orinln passages extendingtnrough` the ring inivar ly trom the lace thereof.

The present invention described herein con-` sists mainly in theprovision oi' a ring havingA a plurality ol' cylinder contacting ribspreferably arranged with ene rib positioned at each end face ol' lthering and with a groove be- 'tween `the ribs so thatthe unit radialpressure.

of the ribs against the cylinder wall will be increased, but the ribswill balance the ring against the cylinder Wall in the saine manner asia comparatively lloroad vcylinder contacting surface Were providedynvaddition 1" provide passages'leadingthrough the ring" from the groove sothat any oil collected inv` thegroove will drain through' the ring andan accumulation of oil to carry rthe ring out of contact with thecylinder wall will be prevented.

One form of piston ring embodying my invention is shown in theaccompanying drawings wherein similar characters are used to designatesimilar parts; Fig. l is a sectional View of a cylinder and a pistongrooved to receive piston rings; Fig. 2 is a view of the ring embodyingmy invention; Fig. 3 is a view from an end face of the ring partly insection; and Figs. l and 5 are sections of the ring along the lines 4 4and 5 5, respectively, and with the ring inserted in a piston groove.

Referring to the figures the piston A is adapted to reciprocate in thecylinder B and has a plurality of ring grooves C in the uppermost ofwhich are, preferably, mounted piston rings of conventional design asindicated at l), but in the lowermost of which is mounted a ring Eembodying my invention. Also, I prefer that the lowerinost groove C hasa plurality of ports F leading inwardly therefrom to the interior of thepiston, for the purpose more fully hereinafter described.

The piston ring E in the form'shown in the figures comprises a resilientsplit band substantially rectangular in shape and hasthe cylindercontacting face thereof constituted by a pair of comparatively narrowcircumscribing ribs G one of which is positioned at each end face of thering. A series of grooves Hare formed inI the piston ring between theribs G and in this embodiment of my invention the grooves terminateshort of one another with resultant axially extending cylindercontacting bars J between adjacent ends of adjacent grooves. In any formof my invention I prefer that a groove H is comparatively wide as shown.The ring also has a plurality of passages which may be in the form ofslots K extending through the ring and preferably of less length andwidth than the grooves H and arranged so that one of the slots leadsfrom each groove to the rear face of the ring.

In operation and use on a piston the circumscribing ribs G will have acomparatively high unit radial pressure against the cylinder wall andthe ribs may be as narrow as desired to obtain the necessary pressurewithout endangering perfect balance of the ring. The grooves H not onlyreduce the cylinder contacting area, but also collect any oil whichmight tend to accumulate between the ring and the cylinder wall and theoil thus co1 lected will drain rearwardly from the grooves y through theslots K and into the space be-l hind the ring in the ring groove of thepiston from where it may drain through the ports F to the crank case ofthe engine. If the ports F are inclined slightly downwardly as shown inthe drawings the draining of the oil from the ring groove will befacilitated.

While the ring E embodying my invention may be placed anywhere on apiston I prefer that it be placed in the lowerinost groove as outlinedabove because if so positioned no gases will find their way past thecircumscribing ribs G into the groove H and through the slots l andports F to the interior of the piston as might happen if the ring wereplaced in the top groove.

As stated above,'l do not propose to limit myself to any one form of thevarious elements comprised in the ring because it is obvious that theymay be changed in size, shape and arrangement without departing from thespirit of my invention as set forth in the claims included below.

What I claim as new and desire to secure by Letters Patent, is

1. A piston ring having the cylinder contacting face thereof constitutedby a pair of comparatively narrow circumscribing ribs, said ring alsohaving a series of comparatively wide grooves arranged peripherallythereof between said ribs and terminating short of one another withresultant axially extending cylinder contacting bars arranged betweenadjacent ends of adjacent grooves, andsaid ring having passagesextending from said grooves rearwardly through said ring, -each of saidpassages being of less length than the groove from which it extends,whereby the cylinder contacting area of said ring will be reducedwithout materially decreasing the total tension of said ring with aresultant increase of radial pressure per unit of remaining cylindercontacting area.

2. A piston ring comprising a resilient split band having the cylindercontacting face thereof constituted by a pair of comparatively narrowcircumscribing ribs one of which is positioned at each end face of saidring, said ring also having a series of comparatively wide groovesarranged peripherally thereof between said ribs and terminating short ofone another with resultant axially extending cylinder contacting barsarranged between adjacent ends of adjacent grooves, and said ring havingan elongated slot extending from each of said grooves in said seriesrearwardly through said ring, each of said slots being of less lengththan the groove from which it extends, whereby the cylinder contactingarea of said ring will be reduced without materially decreasing thetotal tension of said ring with a resultant increase of radial pressureper unit of the remaining cylinder contacting area.

3. A piston ring having the icylinder con tacting face thereofconstituted by a pair of comparatively narrow circumscribing ribs, saidring also having a series of comparatively wide grooves arrangedperipherally thereof between said ribs and terminating short of oneanother with resultant axially extending cylinder contacting barsarranged between adjacent ends of adjacent grooves,

` said ring'having an elongated slot extending ro'meach'of said groovesin said series rearwardly through sadring each of vsaid slots being ofless length and width than the groove from which it extends and beingpositioned substantially centrally axially and circumferentially thereofwhereby the cylinder cony tacting area of said ring will be reducedwithout materially decreasing the total tension of said ring with aresultantincrease of radial pressure.

In witness whereof I have signed Iny name to the foregoingspecification.

DALLAS M. SMITH.

